Induction heating coil constructed to minimize vibration and noise

ABSTRACT

An induction heating coil which is constructed to minimize vibration and noise despite heavy loads and high voltage. The coil includes a tubing formed into a plurality of turns mounted in a frame. The tubing defines a tunnel through which a workpiece travels continuously in the direction of its length. Sectional water-cooled metal plates are placed over the ends of the tunnel and connected with tie bolts. The bolts carry Belleville washers or springs which are tightened to flatness.

United States Patent Emerson et al.

[451 July 4,1972

[54] INDUCTION HEATING COIL I CONSTRUCTED TO MINIMIZE VIBRATION AND NOISE [72] Inventors: William A. Emerson; John A. Redmond,

both of Ellicott City, Md.

[731 Assignee: United States Steel Corporation [22] Filed: May 13, 1971 [211 Appl. No.: 142,870

[52] US. Cl ..2l9/10.79, 219/1069 [51] Int. Cl. ..H05b 9/02 [58] Field ofSearch ..219/10.79, 10.73, 10.69, 10.61,

[56] References Cited UNITED STATES PATENTS 3,424,886 1/1969 Ross ..2l9/10.79

3,485,983 12/1969 Tama et a1. ..2l9/10.69 X 3,497,658 2/1970 Ross ....2l9/10.79 X 3,320,398 5/1967 Armstrong... ..2l9/10.79 3,188,440 7/1965 Wokas ..2l9/10.79 X

Primary IixaminerJ. V. 'lruhc Assistant ExamincrGale R. Peterson Alt0rneyWalter P. Wood [5 7] ABSTRACT An induction heating coil which is constructed to minimize vibration and noise despite heavy loads and high voltage. The coil includes a tubing formed into a plurality of turns mounted in a frame. The tubing defines a tunnel through which a workpiece travels continuously in the direction of its length. Sectional water-cooled metal plates are placed over the ends of the tunnel and connected with tie bolts. The bolts carry Belleville washers or springs which are tightened to flatness.

6 Claims, 2 Drawing Figures INDUCTION HEATING COIL CONSTRUC'I'ED TO MINIMIZE VIBRATION AND NOISE This invention relates to an improved induction-heating coil constructed to minimize vibration and noise.

Although our invention is not thus limited, our coil is particularly useful for reheating continuously cast metal workpieces preliminary to in-line rolling of the workpiece. Conventional practice in continuous-casting is to pass a partially solidified workpiece of indefinite length through a series of water sprays while it is traveling downwardly immediately after it leaves the mold. Next the workpiece travels through a roll rack which changes its direction of travel from vertical or inclined to horizontal. The sprays chill the surface of the workpiece quite drastically, whereby the workpiece ultimately solidifies throughout. As a result, the surface regions cool below the temperature at which the workpiece can be hotrolled. If in-line rolling is practiced, it is necessary to reheat the workpiece to bring its surface temperature back to about 2,000 F or higher before it enters a work-roll stand. This reheating operation is performed by passing the workpiece continuously through suitable heating means located between the final roll rack and the in-line work rolls. In actual practice gas-fired furnaces or a series of induction coils have been used as the heating means.

Ifthe workpiece is of relatively large cross section, such as a 7% inch square billet or a 12-inch square bloom, induction coils used for reheating it to hot-rolling temperature must carry heavy loads at high voltage. A conventional induction coil includes a number of turns of water-cooled insulated copper tubing defining a tunnel" through which the workpiece travels. At the load required, the continual current reversals tend to produce excessive vibrations in the turns of the coil. The resulting noise may exceed the tolerable limit for workmen in the surrounding area.

An object of our invention is to provide an improved induction coil of the foregoing type, which coil can carry heavy loads without excessive vibration or noise.

A further object is to provide a coil of the foregoing type in which the turns are held against vibration by a novel arrangement of sectional metal end plates and tie bolts, and in which we protect the end plates against overheating.

A further object is to provide a coil of the foregoing type which is readily installed in a line or removed with a minimum of parts to be handled.

1n the drawings:

FIG. 1 is a side elevational view with our improved coil; and

FIG. 2 is an end elevational view of our coil.

Our coil includes a large number of turns (54 in one example) of tubing of copper or the like shaped to define a tunnel through which a workpiece W may travel continuously in the direction of its length. In the illustration the workpiece is a billet square in cross section and the turns are square with slightly rounded corners, but the size, shape and number of turns vary with the cross section, composition, and temperature of the workpiece with which the coil is used. The tubing is continuous from end-to-end of the coil and its turns are heavily insulated from one another. The bore of the tubing is divided into sections of a few turns each for cooling purpose. The tubing is mounted within a frame 12. Water inlet and discharge manifolds l3 and 14 are mounted in the lower portion of the frame and extend parallel with the tunnel axis at opposite sides thereof. The inlet manifold 13 has a series of offtakes 15 each connected to a different cooling section of the tubing through respective hoses 16. Likewise the cooling sections are connected to the discharge manifold 14 through hoses l7 and intakes 1 8. The upper face of the tubing carries a hose-supporting bracket 19 through which hoses 17 extend. The manifolds carry quick-disconnect fittings 20 depending below the frame 12 through which cooling water enters and leaves the coil.

Frame 12 is removably mounted on a supporting structure which includes a base 22. The underside of the frame includes a pair of inwardly facing channels 23. Longitudinally extendparts broken away of ing bars 24 are fixed to the lower flanges of channels 23 and are removably bolted to the base 22. The base carries upstanding tapered locating pins 25 received in corresponding holes in bars 24, whereby we may easily position the frame on the base when installing the coil.

The tubing is energized from a pair of terminals 26 and 27 mounted on the underside of frame 12 near one end. Conductors 28 and 29 extend from the respective terminals to locations beneath the ends of the tubing. Flexible connectors 30 and 31 connect the respective conductors 28 and 29 with the tubing to avoid breaking the electrical connection if some vibration occurs.

Frame 12 carries insulating blocks 34 of Transite or equivalent material, which blocks cover opposite ends of the tunnel. We have not described the other insulation around the turns of the tubing, since it may be conventional. In fact, of the structure thus far described, only the quick disconnect fittings 20, the locating pins 25, and the flexible connectors 30 and 31 depart from what we regard as conventional.

In accordance with our invention, we place metal plates, preferably of stainless steel, over the blocks 34. Each plate is formed of a lower section 35 of U-shape in outline and an upper section 36 of inverted U-shape in outline. We extend a plurality of tie bolts 37 through the two lower sections 35 outside the turns 10 end-to-end of the coil and parallel with the tunnel axis. Similarly we extend a plurality of tie bolts 38 through the two upper sections 36. Each tie bolt carries nuts 39 and a plurality of Belleville washers or springs 40. We tighten nuts 39 to the extent that the Belleville washers are substantially flat. With this construction we are able to compress the turns 10 tightly enough that there is very little vibration.

There is a strong tendency for the end plates to be heated by the induction coil. For this reason we divide the plates at each end of the coil into upper and lower sections 35 and 36, as already described. Nevertheless it is possible to divide them in some other way, such as a right and a left. The divided plates still tend to overheat, and for this reason we mount a respective tube 41 over the outer face of each section. We connect tubes 41 with the inlet and discharge manifolds l3 and 14 and then circulate cooling water over the faces of the plates. In this manner we effectively prevent the plates from overheating.

From the foregoing description, it is seen that our invention affords an induction heating coil which can carry heavy loads and yet is free of excessive vibration and noise. Although our coil is particularly useful for reheating continuously cast workpieces, it is apparent it has broader utility where analogous problems are encountered.

We claim:

1. In an induction heating coil, which includes a frame, an insulated electrically conductive tubing mounted in said frame and formed into a plurality of turns defining a tunnel through which a workpiece may travel continuously in the direction of its length, inlet and discharge means for cooling water connected to said tubing, and insulating blocks covering opposite ends of said tunnel, the combination therewith of improved means for minimizing vibration and noise when said coil carries heavy loads at high voltage, said improved means comprising sectional metal end plates covering said blocks, a plurality of tie bolts extending between said end plates end-to-end of the coil, nuts and spring means on said tie bolts capable of being tightened to substantially prevent vibration, and means for water-cooling said end plates.

2. A coil as defined in claim 1 in which each of said plates is divided into a lower section of U-shape in outline and an upper section of inverted U-shape in outline.

3. A coil as defined in claim I in which said spring means are in the form of Belleville washers or springs and said nuts are tightened sufficiently to flatten said washers or springs.

4. A coil as defined in claim 1 further comprising flexible connectors attached to the ends of said tubing through which the tubing is electrically energized.

porting structure therefor, said structure comprising a base to which said frame is bolted, said base having an upstanding tapered locating-pin, said frame having a hole receiving said pin.

Disclaimer 3,674,971.Wz'llz'am A. Emerson and John A. Redmond, Ellicott City, Md.

INDUCTION HEATING COIL CONSTRUCTED TO MIN I- MIZE VIBRATION AND N OISE. Patent dated July 4, 1972. Disclaimer filed Oct. 26, 1973, by the assignee, United States Steel Corporatz'on. Hereby enters this disclaimer to claims 1 to 6 of said patent.

[Oficz'al Gazette March 11, 1975.]

Disclaimer 3,674,971.-William A. Emerson and John A. Redmond, Ellieott City, Md.

INDUCTION HEATING COIL CONSTRUCTED TO MINI- MIZE VIBRATION AND NOISE. Patent dated July 4, 1972; Disclaimer filed Oct. 26, 1973, by the assignee, United States Steel 001'- pomtion. Hereby enters this disclaimer to claims 1 to 6 of said patent.

[Ofiiez'al Gazette March 11, 1.975.] 

1. In an induction heating coil, which includes a frame, an insulated electrically conductive tubing mounted in said frame and formed into a plurality of turns defining a tunnel through which a workpiece may travel continuously in the direction of its length, inlet and discharge means for cooling water connected to said tubing, and insulating blocks covering opposite ends of said tunnel, the combination therewith of improved means for minimizing vibration and noise when said coil carries heavy loads at high voltage, said improved means comprising sectional metal end plates covering said blocks, a plurality of tie bolts extending between said end plates end-to-end of the coil, nuts and spring means on said tie bolts capable of being tightened to substantially prevent vibration, and means for water-cooling said end plates.
 2. A coil as defined in claim 1 in which each of said plates is divided into a lower section of U-shape in outline and an upper section of inverted U-shape in outline.
 3. A coil as defined in claim 1 in which said spring means are in the form of Belleville washers or springs and said nuts are tightened sufficiently to flatten said washers or springs.
 4. A coil as defined in claim 1 further comprising flexible connectors attached to the ends of said tubing through which the tubing is electrically energized.
 5. A coil as defined in claim 1 in which said inlet and discharge means include manifolds mounted in said frame, and quick-disconnect fittings connected to said manifolds and depending therefrom.
 6. In combination, a coil as defined in claim 1, and a supporting structure therefor, said structure comprising a base to which said frame is bolted, said base having an upstanding tapered locating-pin, said frame having a hole receiving said pin. 